Question

Which of the following ions is the brown ring test useful for determining?

(a) NO2^–

(b) NO2^+

(c) NO2

(d) NO3^–

I got this question by my school teacher while I was bunking the class.

My question is taken from P-Block in section P-Block Elements of Chemistry – Class 12

Answer 1

Right answer is (d) NO3^–

To explain: The brown ring test is used to determine the presence of nitrate ions, NO3^–. Dilute ferrous sulfate solution is added to solution containing nitrate ion. Following this, concentrated sulfuric acid is added along the sides of the test tube. A brown ring is formed at the junction concentrated sulfuric acid and solutions.